Technical Field
The present invention relates to a defect observation apparatus.
Background Art
In the production processes of semiconductor devices, if foreign substances or pattern defects, such as breaking of wires and short circuits, (hereinafter, foreign substances and pattern defects shall be collectively referred to as “defects”) are present on a wafer that is a semiconductor substrate, insulation failures of wires, short circuits of wires, and the like may occur. Such defects are mixed due to a variety of causes resulting from the production processes. Therefore, in order to mass-produce semiconductor devices, it is important to detect defects that are generated during a production process at an early stage, find out the source of generation of the defects, and thus prevent a decrease in yield.
A method for identifying a cause of generation of defects that is in widespread use will be described. First, the position of a defect on a wafer is identified using a defect inspection apparatus. Next, the defect is observed in detail with a SEM (Scanning Electron Microscope) or the like on the basis of the identified coordinate information on the defect. Then, a cause of generation of the defect is estimated through comparison of the result of observation with a database.
However, when such an identification method is used, there is a discrepancy between the coordinate system of the SEM and that of another inspection apparatus. Therefore, a defect that has been detected with another inspection apparatus is detected again with an optical microscope mounted on the SEM so that positional information (coordinate information) is corrected and the defect is observed in detail with the SEM on the basis of the corrected coordinate information. Accordingly, it is possible to correct the discrepancy between the two coordinate systems and thus improve the success rate of defect observation. For example, Patent Document 1 discloses a defect observation apparatus that includes an optical microscope and an electron microscope.